The invention relates to a device for alternatively one- or double-sided coating of a running paper web, in which device the final evening-out of the coating is made in a smoothing nip including a roll and a counter piece.
The basic factors of coating are quality and speed. High coating speeds increase productivity, but high speeds make it difficult to fulfil the quality requirements. Nearly all possible design alternatives have been tested on coating devices. The web has been run both from above downwards and from below upwards, and also horizontally as well as aslant at different angles. Coating substance has been applied to the web with rolls, extruders, by spraying, by leading the web through a coating substance container, by forming a coating pond in contact with the web, and in many other ways. Some solutions have proved advantageous in certain applications, but all solutions have usually had considerable drawbacks, and their applicability to coating substances and coating conditions of different types has not been satisfactory.